1. Field of the Invention
The present invention relates to a switching power source apparatus that is highly efficient and involves a low switching loss.
2. Description of Related Art
FIG. 1 illustrates a switching power source apparatus according to a related art. This switching power source apparatus includes a step-up converter and an isolated full-bridge circuit. The step-up converter includes a DC power source Vin, a reactor L1, switching elements Q1 and Q2 of MOSFETs, a current detecting resistor R1, a capacitor C1, and a first controller 101.
According to a voltage from the capacitor C1 and a voltage from the current detecting resistor R1, the first controller 101 turns on/off the switching elements Q1 and Q2 alternately so as to provide, from both ends of the capacitor C1, a constant output voltage Vo2 that is higher than an input voltage from the DC power source Vin.
The isolated full-bridge circuit includes switching elements Q3 to Q6 that are MOSFETs, current detecting resistors R2 and R3, a primary winding P1 and secondary windings S1 and S2 of a transformer T, diodes D1 and D2, a rector L2, a capacitor C2, and a second controller 102.
According to a voltage from the capacitor C2 and voltages from the current detecting resistors R2 and R3, the second controller 102 turns on/off the switching elements Q3 and Q6 alternately and the switching elements Q4 and Q5 alternately so as to provide a constant output voltage Vo1.
With this configuration, the switching power source apparatus of FIG. 1 provides the two output voltages Vo1 and Vo2.
Another related art disclosed in Japanese Unexamined Patent Application Publication No. H09-233822 (Patent Document 1) discloses an AC-DC converter apparatus employing a three-phase inverter module.